Liberation Army (PLA) markings marched towards Irbid, which the fedayeen had declared a "liberated" city. The 40th Armoured Brigade managed to block the Syrian forces' advance after heavy fighting. A second, much larger, Syrian incursion occurred on the same day: it consisted of two armored and one mechanized infantry brigades of the 5th Infantry Division, and around 300 tanks. Although the Syrian tanks had PLA markings, the troops were Syrian Army regulars. Syria issued no statement regarding the situation, but it is believed that the purpose of its intervention was to help the fedayeen overthrow the monarchy. Another tentative explanation is that the Syrians wanted to create a haven for the fedayeen in northern Jordan, from where they could negotiate with Hussein. There were also concerns of Iraqi interference. A 17,000-man 3rd Armoured Division of the Iraqi Army had remained in eastern Jordan since after the 1967 Six-Day War. The Iraqi government sympathized with the Palestinians, but it was unclear whether the division would get involved in the conflict in favor of the fedayeen. Thus, the Jordanian 99th Brigade had to be detailed to monitor the Iraqis. David Raab, one of the plane hijacking hostages, described the initial military actions of Black September: Hussein arranged a cabinet meeting on the evening of the Syrian incursion, leaving them to decide if Jordan should seek foreign intervention. Two sides emerged from the meeting; one group of ministers favored military intervention from the United Kingdom or the United States, while the other group argued that it was an Arab affair that ought to be dealt with internally. The former group prevailed as Jordan was facing an existential threat. Britain refused to interfere militarily for fear of getting involved in a region-wide conflict; arguments such as "Jordan as it is is not a viable country" emerged. The British cabinet then decided to relay the Hussein's request to the Americans. Nixon and Kissinger were receptive to Hussein's request. Nixon ordered the U.S. Navy's 6th Fleet to be positioned off the coast of Israel, near Jordan. By 19–20 September, the U.S. Navy had concentrated a powerful force in the Eastern Mediterranean. Its official mission was to protect American interests in the region and to respond to the capture of about 54 British, German, and U.S. citizens in Jordan by PLO forces. Later, declassified documents showed that Hussein called an American official at 3 a.m. to request