Baitullah Mehsud  (born ca. 1974) is a leading military leader in Waziristan, Pakistan and the leader of the Taliban umbrella group, Tehrik-i-Taliban Pakistan  (TTP), which was officially formed in December 2007. He belongs to the Mehsud tribe in Pakistan's troubled South Waziristan region and is commanding about 20,000 pro-Taliban militants. Mehsud, the most wanted man in Pakistan , was accused of assassinating the former Prime minister Benazir Bhutto. He also claimed responsibility for Lahore Police academy attack  and is thought to be responsible for many such attacks.
Mohsin Segal at Pakistan Spectator  talks about Mehsud's terror tactics:
Pakistan's #1 terrorist is Baitullah Mehsud who has rocked Pakistan from Karachi to Khyber with a continuous string of suicide attacks, bomb blasts, kidnapping and then his other evil tactics. He has garnered support from many quarters and is capable of wrecking havoc throughout Pakistan. His power has not all of a sudden emerged from out of the blue. He has cashed in on the opportunity. He is using the wandering and clueless foreign militants and the local militants, in the name of Islam, as a cannon fodder.
Baituallah mehsud is known to avoid public appearance or photographs. A video by Istream.in shows him and his possible hideout:
On 17th June, the Pakistan army has officially started  an operation against Taliban leader Baitullah Mehsud and his allies in South Waziristan.
Jauhar Ismail at All Things Pakistan  discusses the reasons for the army offensive:
While the military analysts disagree on the timing for this operation, there is no disagreement that crushing Baitullah and his militant network is a prerequisite for curbing the tsunami of terrorism engulfing Pakistan. In addition to providing sanctuary to top level Al-Qaeda leadership, TTP is also running several suicide training camps in South Waziristan. He has also made successful attempts to fuse together various terrorist groups to fight their “common enemies”.
The operation is termed as ‘Rah-e-Nijat’  which means ‘way to good riddance’. In the wake of the operation Rah-e-Nijat several tribe leaders form Baitullah's native tribe have turned against him. Junaid Khan at Pro-Pakistan  gives an insight on the alliance:
Now that the army operation is imminent, a division between the Mehsuds are becoming visible. The tribal people of South Waziristan will have to take sides since remaining neutral will be a difficult option.
Another post at Urdu Maza  emphasizes on the need of the operation:
Its the best time, we have dispersed more than 3.5 million Pakistani, now Pakistan army should clear every militant in north and South Waziristan, enough is enough, northern areas are the backbone of our culture and society, these areas are symbol of purity and beauty and of course a heaven of tourism, but unless these criminals are not wiped out completely, they can create problem again.
With the local tribesman volunteering to help the army and a Rs. 50 million bounty  on Mehsud, it is hoped that the operation will be swift. But Pakistan is facing a growing number of refugees who are fleeing the wars and if this operation continues for long, this will trigger a humanitarian catastrophe.