Turkish warplanes struck Islamic State group targets across the border in Syria on Friday, a day after IS militants fired at a Turkish military outpost killing nine IS fighters.
Turkey, which straddles Europe and Asia and borders the Middle East, had long been reluctant to join the US-led coalition against the extremist group.
In a related, long-awaited development, Turkey said it has agreed to allow US-led coalition forces to base manned and unmanned aircraft at its air bases for operations targeting the IS group.
A Turkish Foreign Ministry statement said Turkey's military would also take part in the operations.
The foreign ministry would not provide details on the agreement, citing operational reasons, but said it expected Turkey's cooperation to "make a difference" to the campaign. The statement did not say which bases would be used, but Turkish media reports said they would include Incirlik, Diyarbakir and Batman, all in southern Turkey near the border with Syria.
Earlier, President Recep Tayyip Erdogan confirmed that Turkey had agreed to let the US use Incirlik airbase for operations "within a certain framework." He did not elaborate on that agreement, which a US official said was reached during a phone call this week with President Barack Obama.
Turkish police also launched a major operation Friday against extremist groups including the Islamic State. They detained more than 290 people in simultaneous raids in Istanbul and 12 provinces.
Prime Minister Ahmet Davutoglu said the airstrikes Friday had "removed potential threats" to Turkey, hitting their targets with "100 percent accuracy." He did not rule out further airstrikes, saying Turkey was determined to stave off all terror threats.
"This was not a point operation, this is a process," Davutoglu said. "It is not limited to one day or to one region ... the slightest movement threatening Turkey will be retaliated against in the strongest way possible."
A government official said three F-16 jets took off from Diyarbakir air base in southeast Turkey early Friday and used smart bombs to hit three IS targets. The official, who spoke on condition of anonymity because of government rules requiring authorization for comment, said the targets were two command centers and a gathering point for IS supporters.
Rami Abdurrahman, who heads the Britain-based Syrian Observatory for Human Rights said the three Turkish airstrikes were all near the border, and struck north of the village of Hawar al-Nahr, east of the Rai area and west of the town of Jarablous.
He said the airstrikes killed nine IS fighters, wounded 12 others and destroyed at least one IS vehicle and a heavy machine gun.
The private Dogan news agency said as many as 35 IS militants were killed in the airstrikes, but did not cite a source.
The Observatory also reported that an airstrike targeted a post near the border with Turkey for al-Qaida's affiliate in Syria, the Nusra Front. It said it was not clear if Turkish warplanes or those of the US-led coalition struck the Nusra Front position.
Davutoglu said Turkish planes did not violate Syrian airspace Friday, but he did not rule out incursions in the future. He denied news reports claiming that Turkey had told the Syrian regime about the airstrikes, but said it had contacted NATO allies before the operation.
The agreement on the Turkish airbases follows months of US appeals to Turkey and delicate negotiations. Asked Friday about the accord, Davutoglu said an agreement that takes Turkey's concerns into account had been reached, but did not elaborate.
Turkey's moves came as the country finds itself drawn further into the conflict in neighboring Syria by a series of deadly attacks and signs of increased IS activity inside Turkey itself.
A government statement said the airstrikes were approved Thursday after IS militants fired from Syrian territory at the Turkish military outpost, prompting Turkish retaliation that killed at least one IS militant.
A funeral was held for the slain Turkish soldier, Yalcin Nane, on Friday, where mourners denounced the IS violence, the state-run Anadolu news agency reported. Officials said Friday's airstrikes were codenamed "Operation Yalcin" in his honor.
The agency said as many as 5,000 police officers were involved in Friday's sweep against suspected extremists, which also targeted the PKK Kurdish rebel group and the outlawed far-left group DHKP-C. Davutoglu said those detained included 37 foreign nationals but did not name their home countries.
One DHKP-C suspect, a woman, was killed in a gunfight with police in Istanbul, Anadolu reported.
The agency said those detained in Istanbul included Halis Bayuncuk, an alleged IS cell leader in the city who is suspected of having helped recruit supporters. Anadolu said Bayuncuk was previously arrested over alleged al-Qaida links and wrote articles for IS publications.
On Monday, a suicide bombing blamed on IS militants killed 32 people in Suruc, a Turkish town near the Syrian border. The bombing ignited protests from Turkey's Kurds, who said the government had not done enough to prevent attacks from the IS group.
Turkish officials say the Suruc bombing could be retaliation for Turkey's crackdown on IS operations. In the last six months more than 500 people suspected of working with the IS group in Turkey have been detained, officials say.