The top US military officer, Admiral Mike Mullen, arrived in Tel Aviv on Sunday for talks with Israeli military and defence officials, both sides said.
"This is a very short visit -- he will meet with Defence Minister (Ehud) Barak and with (Chief of Staff) Gaby Ashkenazi and a few others from the defence establishment," a US embassy spokesman told AFP.
Mullen, who is Chairman of the Joint Chiefs of Staff, was expected to meet Barak at around midday, the Israeli defence ministry said without giving further details.
A military spokesman said the meeting would focus on "cooperation between the two armies and the challenges they have to face," but defence officials quoted by the Jerusalem Post said the two would discuss Iran's nuclear programme and the situation in Syria and Lebanon.
They would also discuss the deterioration in relations between Israel and Turkey in the wake of the disastrous naval raid on a Gaza-bound aid fleet which left nine Turkish activists dead, the paper said.