US Secretary of State Antony Blinken has kicked off his latest urgent Middle East diplomatic mission in Turkiye, as fears mount that Israel’s war against Hamas in Gaza may explode into a broader conflict.

Blinken’s fourth visit in three months comes amid worrying developments outside of Gaza, including in Lebanon, northern Israel, the Red Sea and Iraq, that have put intense strains on what had been a modestly successful US push to prevent a regional conflagration in the weeks after the war began, and growing international criticism of Israel’s military operation.

Blinken was meeting on Saturday with Turkish President Recep Tayyip Erdogan and Foreign Minister Hakan Fidan to discuss what Turkiye and others can do to exert influence, particularly on Iran and its proxies, to ease soaring tensions, speed up humanitarian aid deliveries to Gaza and begin in earnest to plan for reconstruction and governance of postwar Gaza, much of which has been reduced to rubble by three months of intense Israeli bombardments.

The immediate difficulty of Blinken’s task was underscored just hours before his talks with Erdogan as Lebanon’s Iran-backed Hezbollah militia fired dozens of rockets at northern Israel, warning that the barrage was just an initial response to the targeted killing, presumably by Israel, of a top leader from the allied Hamas group in Lebanon’s capital earlier this week.

Meanwhile, stepped-up attacks on commercial shipping in the Red Sea by Yemen’s Iran-backed Houthi rebels have disrupted international trade and led to increased efforts on the part of the US and its allies to patrol the area and respond to threats, including possibly taking direct action against the group at its bases in Yemen.

The Houthis have carried out at least two dozen attacks in response to the Israel-Hamas war in Gaza just since December 19, which have further heightened tensions and raised risks for the global economy.

In Istanbul, US officials said Blinken would be seeking Turkish buy-in, or at least consideration, of potential monetary or in-kind contributions to reconstruction efforts and some form of participation in a proposed multi-national force that could operate in or adjacent to the territory.

Turkiye, and Erdogan in particular, have been harshly critical of Israel and Israeli Prime Minister Benjamin Netanyahu for the prosecution of the war and the impact it has had on Palestinian civilians.

In addition, officials said, Blinken will stress the importance the US places on Turkiye ratifying Sweden’s membership in NATO, a long-delayed process that the Turks have said they will complete soon. Sweden’s accession to the alliance is seen as one critical response to Russia’s invasion of Ukraine.

From Turkiye, Blinken will travel to Turkish rival and fellow NATO ally Greece to meet Prime Minister Kyriakos Mitsotakis at his residence on the Mediterranean island of Crete. Mitsotakis and his government have been supportive of US efforts to prevent the Gaza war from spreading and have signalled their willingness to assist should the situation deteriorate further.

Greece has also shown patience in waiting for the delivery of advanced US fighter jets as the issue of Sweden’s accession to NATO is worked out with Turkiye.

Blinken will end his Saturday in Jordan, which apart from Israel has been the secretary’s most frequent stop on his recent Middle East tours. Jordan will be the first Arab nation on Blinken’s current tour, and will be followed by Qatar, the United Arab Emirates and Saudi Arabia on Sunday and Monday. Blinken will then visit Israel and the West Bank on Tuesday and Wednesday before wrapping up the trip in Egypt.

“We don’t expect every conversation on this trip to be easy,” State Department spokesman Matthew Miller said shortly before Blinken departed Washington late Thursday.

“There are obviously tough issues facing the region and difficult choices ahead. But the secretary believes it is the responsibility of the United States of America to lead diplomatic efforts to tackle those challenges head-on, and he’s prepared to do that in the days to come.”