Please answer a question about the following article about Gamal Abdel Nasser:

On 14 July, Iraqi army officers Abdel Karim Qasim and Abdel Salam Aref overthrew the Iraqi monarchy and, the next day, Iraqi prime minister and Nasser's chief Arab antagonist, Nuri al-Said, was killed. Nasser recognized the new government and stated that "any attack on Iraq was tantamount to an attack on the UAR". On 15 July, US marines landed in Lebanon, and British special forces in Jordan, upon the request of those countries' governments to prevent them from falling to pro-Nasser forces. Nasser felt that the revolution in Iraq left the road for pan-Arab unity unblocked. On 19 July, for the first time, he declared that he was opting for full Arab union, although he had no plan to merge Iraq with the UAR. While most members of the Iraqi Revolutionary Command Council (RCC) favored Iraqi-UAR unity, Qasim sought to keep Iraq independent and resented Nasser's large popular base in the country.

Why did Jordan and Lebanon seek outside aid?
to prevent them from falling to pro-Nasser forces