With Israel war zone visit, Biden's personal diplomacy put to the test: ANALYSIS

President Joe Biden headed to Israel Tuesday evening in a dramatic show of support for a key U.S. ally, while sending a strong message to Iran and Hezbollah to not interfere in the growing crisis.

But in making a personally dangerous visit to an active war zone, he also is taking a high-stakes political gamble.

He needs to walk away from this trip with the more than just an endorsement of Israel's right to defend itself. He needs to show his visit made a difference. And he runs the risk of coming up empty-handed.

He must walk a fine line between seeking to reaffirm America's rock-solid support for Israel while at the same time urging restraint in its expected incursion into Gaza and insisting Israel allow humanitarian aid into the enclave.

The White House has said he will focus on the "critical need for humanitarian assistance to get into Gaza, as well as the ability for innocent people to get out."

What Biden can achieve through personal diplomacy, though, was quickly put in doubt.

Just hours before he was set to leave, the Gaza Health Ministry reported at least 500 people were killed by a blast at a hospital that serves as a shelter for residents who fled their homes. Gazan health authorities said the explosion was caused by an Israeli airstrike. The Israeli Defense Forces denied responsibility. The White House was not commenting.

Following the explosion, Palestinian Authority President Mahmoud Abbas canceled a scheduled meeting with Biden in Jordan and shortly after that -- the entire Jordan leg of his visit was called off.

A White House official said Biden was postponing a meeting as well with Jordan's King Abdullah and Egypt's President Abdel Fattah Al- Sisi, calling it a "mutual decision."

As he flew to Israel overnight on Air Force One, he issued a statement, saying, "I am outraged and deeply saddened by the explosion at the Al Ahli Arab hospital in Gaza, and the terrible loss of life that resulted. Immediately upon hearing this news, I spoke with King Abdullah II of Jordan, and Prime Minister Netanyahu of Israel and have directed my national security team to continue gathering information about what exactly happened," he said. "The United States stands unequivocally for the protection of civilian life during coNFLict and we mourn the patients, medical staff and other innocents killed or wounded in this tragedy."

So far, the diplomatic efforts by Secretary of State Antony Blinken, who has been meeting with leaders in the region ahead of Biden's trip, have had little success.

Despite negotiations with Egyptian and Israeli counterparts, the Rafah border crossing remained closed as of Tuesday night. No aid has been let into Gaza and no Palestinians have been let out. The estimated 2 million civilians in Gaza are trapped and suffering, with fuel, water and electricity running out.

While Biden has issued repeated strong warnings in recent days about protecting innocent civilians, the image of him standing side-by-side with Netanyahu could tie him more closely to the bloodshed in Gaza. His attempts to negotiate more humanitarian aid to Palestinians could be drowned out by the devastating attacks hitting civilians.

Underscoring that challenge are comments from King Abdullah at a news conference Tuesday, calling the iNFLux of refugees into Jordan or Egypt a "red line."

"I think that is the plan by certain of the usual suspects to try and create de facto issues on the ground," he said. "No refugees in Jordan, no refugees in Egypt."

The rapidly deteriorating situation in Gaza and continued bombing that kills civilians could sour global opinion against Israel and Biden's support of the U.S. ally.

That negative opinion could be exacerbated if the ground war begins while Biden is on the ground or if it begins shortly after he leaves.

As if to highlight the possible limits of what Biden can achieve, White House National Security Council spokesman John Kirby said the U.S. did not get any guarantees from Israel about delaying its ground invasion for the visit, saying "we're not dictating terms or operational directions to the Israelis."