Israel Prime Minister Benjamin Netanyahu and his British counterpart Boris Johnson shook hands in front of 10 Downing Street on Thursday.
The Israeli leader was in London on a visit that had not been briefed beforehand by either country.
Netanyahu will also meet US Secretary of Defense Mark Esper while in London, the prime minister’s office said.
US Vice President Mike Pence also met with Johson in Downing Street on Thursday.
Netanyahu was set to go to India this week but cancelled citing commitments concerning Israel's upcoming general elections.
The leader's election campaign was complicated by corruption allegations, making the result difficult to predict.
He spoke with Esper on the phone on Tuesday, in the midst of negotiating a statement of support with the White House to protect Israel security.